Boom assembly for front end loaders



Jan. 16, 1968 F. J. HOPPE 3,363,792

BOOM ASSEMBLY FOR FRONTEND LOADERS Filed DeG. 2O,- 1965 2 Sheets-Sheet l I Q I3 20 y l y Q2 I 26E 5A f2 'a8 /6 50 INVENTOR Frede/Ick J. Hoppe Jan 16, 1968 F. J. HOPPE 3,363,792

BOOM ASSEMBLY FOR FRONTEND LOADERS Filed Deo. 2o, 1965 2 sheets-sheet 2 Il 35 Y 20 i A 50 d @MC/ 1mi 36 y 1w' I M UI /0 l-B l 'l I (il, I L@ v 32 /zl I Iv* Il. 22 O fr A I/d' MMIU "i Fig-3- N Frederick J. Hoppe RN S INVEN TOR United States Patent O 3,363,792 BOOM ASSEMBLY FOR FRONT END LOADERS Frederick J. Hoppe, Overland Park, Kans., assignor to Pacific Car and Foundry Company, Renton, Wash., a corporation of Washington Filed Dec. 20, 1965, Ser. No. 515,035 15 Claims. (Cl. 214-776) ABSTRACT OF THE DISCLOSURE An assisting system for the swingable boom of a front end loader which system is self contained and operates indpendently of the conventional operating mechanism of such a loader. The system is in the form of energy storing means, such as piston and cylinder assemblies operable from a closed pressure system and which are coupled to the boom so that energy is conserved by the system when the boom is lowered and this energy is utilized when the boom is raised to assist in balancing the boom, freeing other power sources to lift the load.

This invention relates to front end loaders and, more particularly, to a boom assembly for such loaders wherein there is provided means for balancing the boom assembly and bucket during swinging movement of the boom assembly to thereby conserve energy and permit the handling of a greater pay load.

It is the primary object of this invention to provide, in combination with a boom assembly for front end loaders, which boom assembly is swingably connected to a tractor, means for counterbalancing the weight of the boom and the empty bucket, the bucket being carried at the normally outermost end of the boom; said balancing or counterbalancing means including at least one piston and cylinder assembly which interconnects the boom assembly and the frame of the tractor.

It is another important aim of this invention to provide a closed static pressure system for the assisting cylinder or cylinders, which system, and therefore the piston and cylinder assemblies which may be coupled therewith, is operable independently of the means for swinging the boom assembly and the other means for pivoting the bucket.

The provision of an assisting system such as will be hereinafter descn'bed, provides means for exerting a pulling force on the boom assembly and bucket during the swinging movement of the boom and bucket, which assisting assembly, in effect, balances or counterbalances the boom assembly and its bucket whereby to permit the power provided for the lifting and tilting means to be applied in handling the pay load carried by the bucket. With the provision of such an assisting assembly there is provided increased breakout force; increased production due to a faster lifting speed; increased over-all machine efficiency; and a lower operating cost for the machine.

Other important aims of this invention include details of construction which will become apparent from the following specification and accompanying drawings, where- 1n:

FIGURE l is a fragmentary, side elevational View of the boom assembly for a front end loader showing the same in a lowered position;

FIG. 2 is a fragmentary, top plan View of the boom assembly;

FIG. 3 is a fragmentary, side elevational view of the boom assembly showing the same in a raised position with the components in a substantially horizontal position; and

FIG. 4 is a schematic view of the pressure system for the piston and cylinder assemblies which assist in the swinging movement of the boom assembly.

A front end loader conventionally includes a tractor 10 of suitable construction whereby to present a frame 12 at the normally forwardmost end thereof, the frame 12 being suitably supported by a wheel and axle assembly 13, the boom assembly 14 being carried by the frame 12 in a manner which will hereinafter be described. It will be appreciated that the tractor may be of any suitable construction; may be wheeled or provided with tracks; may be a rigid frame; or may be articulated depending upon the characteristics desired therein. The specic type of tractor forms no part of this invention.

The boom assembly 14 includes a pair of boom arms 16 which are identical in construction, the boom arms 16 having one end thereof swingably connected to the frame 12 as by a pivot pin 18. The other ends of the boom arms 16 are connected to a bucket 20 by means of pins 22, the bucket 20 normally being disposed forwardly of the tractor 1l). A pair of rams 24 are provided for imparting swinging movement to the boom arms 16, there being a ram 24 coupled to each of said boom arms by means of plates 26, there being a pair of plates 26 afxed to each of the arms 16, the rod end of each ram 24 being pivotally secured to its pair of corresponding plates as by a pin 28, the head end of each ram being pivotally secured to the frame 12 by pins 30.

The boom assembly also includes means for pivoting the bucket 20, said means including a pair of tilting cylinders 32, each having the head end thereof pivotally connected to the frame 12 by a pin 34, the rod end of cylinders 32 being pivotally connected to a lever 36 by a pin 38, the levers 36 each, in turn, being connected to the bucket 2t) by means of a corresponding toggle arm 40,

" there being a pivotal interconnection 42 between each lever 36 and its corresponding toggle arm 40, and a similar pivotal interconnection 44 between the toggle arm 40 and a flange 46, which flange 46 is affixed to the rear of the bucket 20.

Rams 24 and tilting cylinders 32 are each doubleacting and are suitably coupled with pump, conduit and valve means (not shown) whereby rams 24 and cylinders 32 may be selectively operated by the operator of the front end loader to swing the boom assembly 14 from a lowered to a raised position and return the same from a raised to a lowered position, the cylinders 32 being utilized to control the attitude of the bucket 20 in the various positions of the boom assembly 14. Normally, when the boom assembly 14 is in a lowered position, the bucket is disposed as shown in FIG. l, whereby the same may be moved forwardly into a pile of material or the like and loaded, the bucket then breaking out of the material and being lifted by the boom assembly 14 under the urging of rams 24. When this loading and lifting is being accomplished in the conventional front end loader, the entire power provided therefor is normally obtained from the engine of the tractor which operates the pumps to provide pressure in rams `24 and tilting cylinders 32, it being appreciated that when bucket 20 is loaded and lifted, considerable additional power is required and thus additional strain is placed upon the engine which is responsible for the operation of the rams 24 and the tilting cylinders 32.

In the present invention, means are provided for assisting in the swinging movement of the boom `assembly 14, whereby the load on the engine of the tractor is substantially decreased during breakout and lifting operations so that the engine will only be called upon to provide the power to lift the load in the bucket.

This is accomplished by providing means for counten balancing the weight of the boom assembly and bucket, these means including a pair of piston and cylinder assemblies 48, in the embodiment chosen for illustration, each piston and cylinder assembly having the rod end thereof pivotally connected to the frame 12 as at 50 and the head end thereof pivotally connected to a corresponding pair of plates 26 as by a pin 52.

A pressure system is provided for supplying a predetermined pressure to the piston and cylinder assemblies 43, this pressure system including a source 54 of gas under pressure, nitrogen being chosen for purposes of illustration; the source 54 being coupled with suitable piping means such as 56 whereby gas under pressure may be delivered to within each of the cylinders 58 of the assemblies 48 to thereby urge the pistons d@ thereof in the desired direction. The system is provided with an air-overoil intensifier 62 which not only serves to lubricate piston and cylinder assemblies 48, but, due to its slightly higher oil pressure, prevents gas leakage. To replenish the oil, at required intervals, a pump 64 introduces oil into a piping system 56 through a valve `68, the oil being piped as shown in FG. 4, to the components of the piston and cylinder assemblies 48.

The piston and cylinder assemblies 48 are carefully positioned with respect to the boom assembly 14 and are disposed in such a manner that, when the boom assembly 14 and the bucket 20 are in the substantially horizontal position as shown in FIG. 3 of the drawings, there is a right triangular relationship between the pivot point 50 of the rod end of each piston and cylinder assembly 48; the point 18 of pivotal connection of the corresponding boom arm 16 to the frame 12; and the point 52 of pivotal connection of the head end 52 of the piston and cylinder assembly 48 to the plate members 26 which are affixed to boom arm 16, this right triangular relationship extending between points A, B and C as shown in FIG. 3 of the drawings.

Thus, the torque provided by the piston and cylinder assemblies 48 is always equal and opposite to the boom assembly and bucket, whereby the assemblies 48, in effect, balance or counterbalance the boom as it is moved in its swinging position. Thus, inasmuch as the assemblies 48 and their corresponding pressure systems may be utilized to balance the boom assembly 14, it is seen that the Weight thereof is handled by the assemblies 48 in such a manner that the power of the engine may be utilized to lift the pay load in bucket 20 inasmuch as the components of the boom assembly are, in elfect, lifted by the assemblies 48 which exert a pulling action on the boom assembly as it is swung from a lowered to a raised position after the bucket has been loaded. Inasmuch as assemblies 48 are operable independently of the rams 24 and tilting cylinders 32, the operation of said assemblies 48 does not place a drag on the engine utilized to operate rams 24 and cylinders 32 so that the power thereof may be provided to lift the pay load in the bucket 20.

Thus, there is provided in a boom assembly for a front end loader an assisting system which is constructed and disposed in such a manner that it will, in effect, balance the boom assembly and bucket, freeing other power sources to be devoted to the lifting of the load in the bucket. It Will be appreciated that no external power or actuating means are required for the closed system which actuates assemblies 48. The power to exert a predetermined pull upon the boom assembly as it moves through the breakout and lifting operations is supplied entirely by the internal energy of the pressurized gas stored in cylinder 54.

Having thus described the invention, what is claimed as new and desired to be secured by Letters Patent is:

1. In a front end loader,

a tractor;

a boom assembly having one end thereof swingably connected to the tractor;

a bucket pivotally mounted on the other end of the boom assembly;

means for swinging said boom assembly between a raised and a lowered position;

means for pivoting said bucket;

energy means coupled With the tractor and the boom assembly, said means conserving energy as the boom is lowered and utilizing said conserved energy to assist in balancing the boom when it is raised, said energy storing means including at least one piston and cylinder assembly having one end thereof coupled to the tractor and the other end thereof coupled to the boom assembly.

2. A front end loader as set forth in claim 1, said piston and cylinder assembly being operable independently of the means for swinging the boom assembly and independently of any external power source.

3. A front end loader as set forth in claim 2, there being a closed pressure system in communication with said piston and cylinder assembly for operating the same.

4. A front end loader as set forth in claim 3, the pressure in said system and therefore in said piston and cylinder assembly being sufficient to balance the boom `assembly and bucket when the bucket is empty.

5. A front end loader as set forth in claim 4, said pressure system including a source of gas under pressure and piping means for delivering said gas to said piston and cylinder assembly.

6. A front end loader as set forth in claim 5, the head end of said piston and cylinder assembly being pivotally coupled to the boom assembly, the rod end being pivotally coupled to the tractor.

7. In a front end loader,

a tractor having a frame;

a boom assembly having one end thereof swingably connected to the frame, said boom assembly including a pair of spaced-apart boom arms;

a bucket pivotally mounted on the other end of the boom assembly;

a pair of rams for swinging said boom assembly, there being a ram for each arm;

means for controlling the attitude of the bucket; and

energy storing means coupled with the tractor and the boom assembly, said means including a piston and cylinder assembly for each arm, said means conserving energy as the boom is lowered and utilizing said energy to assist in balancing the boom when it is raised.

8. A front end loader as set forth in claim 7, said piston and cylinder assemblies being operable independently of said rams.

9. A front end loader as set forth in claim 8, there being plate means fixed to each of said boom arms, the ram corresponding to each arm having the rod end thereof pivotally attached to said plate means thereon, the piston and cylinder assembly corresponding to each arm having the head end thereof pivotally attached to the plate means thereon.

10. A front end loader as set forth in claim 9, the head end of each yram being pivotally attached to the tractor frame, the rod end of each piston and cylinder assembly being pivotally attached to the tractor frame.

11. A front end loader as set forth in claim 10, there being a closed pressure system in communication with said piston and cylinder assemblies for simultaneously operating the same.

12. A front end loader as set forth in claim 11, the pressure in said system and therefore deliverable to said piston and cylinder assemblies being suicient to counterbalance the boom assembly and bucket When the bucket is empty.

13. A front end loader as set forth in claim 12, said pressure system including a source of gas under pressure and piping means placing said source in communication with said piston and cylinder assemblies.

14. A front end loader as set forth in claim 10, the point of attachment of the rod end of each piston and cylinder assembly to the frame, the point of connection of. said one end of the boom to the frame and the point of attachment of the head end of each piston and Cylinder assembly to the plate means being in right triangular relationship when the boom is in a substantially horizontal position.

15. A front end loader as set forth in claim 13, there being means in selective Communication with said pressure system and therefore With said piston and cylinder assemblies for delivering a lubricant under pressure thereinto, the pressure of said lubricant being greater tl of the gas in said system.

References Cited UNITED STATES PATENTS 999,982 1/1909 Eingaman 214-775 1,527,251 2/1925 Furst 214-775 X 2,426,544 8/1947 Wooldridge 214-773 FOREIGN PATENTS 614,052 6/1935 Germany.

ian that 10 HUGO o. SCHULZ, Pffmary Examiner, 

